Track type drafting machine

ABSTRACT

THE TRACK TYPE DRAFTING MACHINE OF THE PRESENT INVENTION COMPRISES SEVERAL IMPROVEMENTS IN OR ON THE CONSTRUCTIONS OF A CURSOR SLIDABLY MOUNTED ON A TRANSVERSE TRACK OF A TRACK TYPE DRAFTING MACHINE, A MEMBER CONNECTING A DRAFTING HEAD WITH A SCALE OR RULE UNIT TO ANOTHER CURSOR SLIDABLY MOUNTED ON A LONGITUDINAL TRACK ASSOCIATED WITH THE TRANSVERSE TRACK IN PERPENDICULAR RELATIONSHIP THEREWITH, MEANS FOR PREVENTING NOISY SOUNDS WHICH OCCUR IN MOVEMENTS OF THE A BALANCE WEIGHT WITHIN THE LONGITUDINAL TRACK, MEANS FOR PREVENTING A DAMAGE CAUSED BY AN ACCIDENTAL DROP OF THE BALANCE WEIGHT, AND MEANS FOR EXERTING AN APPROPRIATE TENSION IN ROPES HOLDING THE BALANCE WEIGHT.

Feb. 23, 1971 SEIICHI KOMURA TRACK TYPE DRAFTING MACHINE 3 Sheets-Sheet 1 Filed March 20 1969 INVENTOR SEHCHI KOMURA ATTORNEY Feb. 23, 1971 SEIICHI KOMURA TRACK TYPE DRAFTING MACHINE 5 Sheets-Sheet 2 Filed March 20 i969 INVENTOR SEIICHI KOMURA Feb. 23, 1971 SEHCHI KOMURA 3,564,720

TRACK TYPE DRAFTING MACHINE Filed March 20, 1969 3 Sheets-Sheet 3 INVENTOR SEHCHI KOMURA TTORNEY 3,564,729 Patented Feb. 23, 1971 'Q ICC 3,564,720 TRACK TYPE DRAFTING MACHINE Seiichi Komura, Osaka, Japan, assignor of one-half to Muto Kogyo Kabushiki Kaisha, Tokyo, Japan Filed Mar. 20, 1969, Ser. No. 808,909 Claims priority, application Japan, Apr. 2, 1968, IS/26,112; Apr. 12, 1968, 43/29,598; Apr. 23, 1968, 43/33 236; May 3, 1968, 43/36,075; May 7, 1968, 43/37,1 3

Int. Cl. 13431 13/02 US. Cl. 3379 2 Claims ABSTRACT OF THE DISCLOSURE The track type drafting machine of the present invention comprises several improvements in or on the constructions of a cursor slidably mounted on a transverse track of a track type drafting machine, a member connecting a drafting head with a scale or rule unit to another cursor slidably mounted on a longitudinal track associated with the transverse track in perpendicular relationship therewith, means for preventing noisy sounds which occur in movements of a balance weight within the longitudinal track, means for preventing a damage caused by an accidental drop of the balance weight, and means for exerting an appropriate tension in ropes holding the balance weight.

BACKGROUND OF THE INVENTION This invention relates to a track type drafting machine comprising a transverse track, a transverse cursor slidably mounted on the transverse track, a longitudinal track associated with the transverse track through the transverse cursor in perpendicular relationship with the transverse track, a longitudinal cursor slidably mounted on the longitudinal track, a drafting head assembly including a scale or rule unit and fixedly connected to the longitudinal track, means for balancing the drafting head assembly mounted in the interior of the longitudinal track, a tail roller means mounted on the longitudinal track at an end opposite to the transverse cursor for holding the longitudinal track in parallel to a drafting board, and locking means for rigidly securing the drafting machine to the drafting board. The invention relates more particularly to the track type drafting machine, comprising an improved transverse cursor, improved drafting head mounting member, improved means for preventing noisy sounds which occur in movements of a balance weight Within the longitudinal track, improved means for preventing a damage caused by an accidental drop of the balance weight, and improved means for exerting an appropriate tension in ropes holding the balance of weight.

An object of the invention is to provide an improved track type drafting machine having several advantages over the previous drafting machines of this type.

DESCRIPTION OF THE DRAWING FIG. 1 is a perspective, general view of a track type drafting machine in accordance with the present invention, with a drafting board shown in phantom lines.

FIG. 2 is a plan view of a transverse cursor.

FIG. 3 is an elevational view of FIG. 2 having a partial sectional view.

FIG. 4 is a perspective view of a longitudinal cursor when viewed it from the bottom thereof, and showing the connection between the longitudinal cursor and the drafting head assembly.

FIG. 4A is an enlarged fragmental side view.

FIG. 5 is a plan view of a drafting head assembly.

FIG. 6 is a sectional view of a drafting head assembly taken along line 6--6 in FIG. 5.

FIG. 7 is a cross-sectional view of the longitudinal track alone, taken along line 66 in FIG. 1.

FIG. 8 shows a fragmentary section taken along line 7-7 in FIG. 7.

FIG. 9 is a perspective view of a balance weight provided with a plurality of grooves to prevent noisy sounds.

FIG. 10 shows the grooved balance weight located in the longitudinal track.

Referring now to FIG. 1 illustrating a preferred embodiment of the invention, the track type drafting machine generally designa-ted by numeral 10 comprises a transverse track 11 and a longitudinal track 12 mounted on the transverse track in perpendicular relation therewith. The transverse track 11 is preferably of hollow rectangular cross section with upper flanges 13 as illustrated at 14, and the longitudinal track is also preferably of hollow rectangular cross section, but provided with lower flanges 15 as illustrated at 16. The transverse track 11 includes caps 17 at its opposite ends, clamping means 18 adjacent the ends for fixedly securing the transverse track 11 to a drafting board 19 and a transverse cursor 20 improved in accordance with the invention and slidably mounted on the transverse track 11 and carrying the longitudinal track 12 in sliding relation therewith. The construction and function of the cursor will be described in detail hereinafter. The longitudinal track 12 includes at its opposite ends an upper cap 21 and lower cap 22 improved in accordance with the invention whose construction and function will be described in detail hereinafter, a longitudinal cursor 23 slidably mounted on the longitudinal track 12 and carrying a drafting head assembly 24 through a connecting element 25 improved in accordance with the invention, whose construction and function will be described in detail hereinafter, tail roller means 26 for holding the longitudinal track '12 in a parallel plane to the surface of the drafting board 19, and a balance means 27 (FIG. 7) improved in accordance with the invention whose construction and function will be described in detail hereinafter.

Referring to FIGS. 2 and 3, there is shown the transverse cursor 20 improved in accordance with the invention. It includes a base block 30 slidably mounted on the transverse track 11 by means of engagement of the inwardly extending lower edges (not shown) of the base block 30 with the upper flanges 13 of the transverse track 11, which base block 30 is provided with a pair of spaced lugs 31. Disposed between and secured to the lugs 31 with set screws 32 and nuts 33 is a longitudinal track mounting member 34 having a dovetail groove 35 to receive the lower flanges 15 of the longitudinal track 12 and a central recess 36. at its top surface, and a gap 37 at its one side. The mounting member 34 has a transverse bore 38 extending beyond the gap 37 into the central portion thereof to receive a set bolt 39 which acts to lock the longitudinal track in the mounting member. The outer portion of the bore 38 has a diameter greater than that of the set bolt 39, while the inner portion has internal threads to engage the external threads of the set bolt 39. The transverse cursor 20 includes means 40 for locking the same to the transverse track 11 at required positions.

With this arrangement, by screwing the set bolt 39 in the mounting member 34, thereby constricting the gap 37, the lower flanges 15 of the longitudinal track 12 loosely received in the dovetail groove 35 are tightly locked therein, and by unscrewing the screw bolt 39 thereby releasing the constriction of the gap 37, the longitudinal track 12 may freely be moved in its axial direction relative to the cursor 20 or the transverse track 11.

The advantage of the cursor 20 is able to accommodate the existing track type drafting machine 10 to a drafting board having a width shorter than the length of the longitudinal track 12 by moving the latter until the tail roller means 24 usually fixedly mounted on the extreme end of the longitudinal track becomes seated on the lower edge portion of the drafting board, as for example shown in FIG. 1. If the longitudinal track 12 lacks means to move the same, the lower end thereof will be left in a projected position, and will strike the body of the draftsman. This is obviously objectionable to drafting operations. Another advantage of the present transverse cursor is that the longitudinal track 12 may be turned upwards about the common horizontal axis of the set screws 32, after slightly releasing them, for cleaning the upper surface of a drafting paper, or renewing a drafting paper. Another advantage is able to make the size of the packed drafting machine compact by removing the longitudinal track 12 from the transverse cursor and piling up on the transverse track 11.

The longitudinal cursor 23 illustrated in FIG. 4 shows its bottom with other members such the longitudinal track 12 and the drafting head assembly 24, and has at its four corners circular lugs 45 whose circumferences are slidingly engaged by the lower flanges '15 of the longitudinal track 12, and a locking means 46 to fix the longitudinal cursor 23 to the longitudinal track 12.

The drafting head assembly 24 illustrated in FIG. comprises a dial plate 50, a knob 51 and a rule or scale unit 52. The drafting head assembly 24 is no part of the invention, but an explanation thereof will now be made. Generally speaking, upon turning the kob 51, the rule or scale unit 52 rotates through an angle corresponding to the turn of the knob 51 relative to the dial plate 50 that is kept stationary. The dial plate 50 includes an insert plate 53 and an upper plate 54, and they are held together by means of bolts 55 (only one being shown) and have a common aperture 56. The outer end of the insert plate 53 is normally rigidly connected to an end of the connecting element 25 in accordance with the present invention by the threaded portion 57 of a locking means 70. The opposite end of the connecting element 25 is rigidly secured to the longitudinal cursor 23' as shown in FIG. 1. With this arrangement, the dial plate 50 is 'kept stationary relative to the rotatable rule or scale unit 52.

The rule or scale unit 52 comprises two mutually perpendicular scales 58 and 59, and a support 60 having a reference mark element 61. An end of the support opposite to the scales 58 and 59 extends under the dial plate 50 and is provided with an aperture 60 aligned with the aperture 56. The toothed wheel 62 (only its section being shown) is disposed between the dial gauge 50 and the extension of the support 60, and mounted on the bottom surface of the extension is a cover 63 for protection thereof. The toothed wheel 62, the extension of the support 52 and the cover 63 are held together by means of set screws 64 and 65 and bodily and fixedly connected to the knob 51 through bolt-nut means 66 passing through the apertures 72 and 56. Though there is not illustrated in the drawings, the dial plate 50 includes a spring biased pawl rigidly secured to the under surface thereof and engageable with the tooth of the toothed wheel 62 to stop the rule or scale assembly 52 at a desired angular position. With this arrangement, either edge of the scales 58 and 59 may be in alignment with a predetermined reference line obliquely drawn relative to the axis of the vertical track 111 or the longitudinal track, on the drafting paper, by turning the knob 51. It is obvious that the knob 51 may be used for shifting the longitudinal cursor 23 along the longitudinal track 12.

A locking means 67 (FIG. 5 or FIG. 1) on the dial plate is to fasten the rotatable support 52 and stationary dial plate 50 together, and a project 68 shown projected on the dial plate 50 is means for operating the above-mentioned spring biased pawl in such a manner that when the project 68 is manually pushed inwards, the

spring biased pawl is disengaged with the toothed wheel 50 so as to permit the toothed wheel 61 to freely rotate about the bolt-nut means 66, and upon releasing the project 68, the spring biased spring may engage the toothed wheel 61 at any position between the crests of adjacent teeth. The necessity of the project 68 is caused from the fact that the pitch of the teeth of the toothed wheel 61 must have a certain chordal length measurable with angle, for example, as 15", that is usually determined by the size of the wheel and the machining practice, consequently the pawl is impossible to positively occupy a position within a range less than 30, if the project 68 was not provided there. The upper plate 54 arranged above the dial plate 50 includes an elongated slot 69 through which the locking means 70 passes with the threaded portion 57 thereof being normally tightly engaged with the connecting element 25 as described hereinbefore. By slightly releasing the contact between the insert plate 53 and the connecting element 25 for turn of the insert plate 53, the calibration of the dial plate 50 relative to the angular position of the rule or scale unit may be accomplished. A stopper 7.1 on the outer end of the upper plate 54 is provided for preventing an excess unscrewing of the threaded portion 57.

The connecting element 25 in accordance with the invention is characterized by the connecting element being made of a resilient material to thereby operate as a flat spring. It will be understood that the component of the gravity of the drafting head assembly 24 including the rule or scale unit 52 in the direction normal to the drafting board 19 will be reduced as the inclination of the drafting board 19 to a horizontal plane is increased, thereby the press of the rule or scale unit 52 against the paper on the drafting board 19 will be reduced. Nevertheless, by the use of the connecting element 25 resiliently yieldable to relatively small forces, a positive contact of the rule or scale unit 52 with the drafting paper may be assured in spite of the great inclination of the drafting board 19.

Referring to FIGS. 7 and 10, there is illustrated a balance means 27 for balancing the drafting head assembly 24. The balance means 27 is substantially disposed within the longitudinal track 12 and comprises a balance weight 75, sheaves 76 and 77 located adjacent to the opposite ends of the longitudinal track 12, and a pair of ropes 78a and 78b connecting the balance weight to the longitudinal cursor 23 at their respective ends after trailing around the sheaves 76 and 77 respectively. With this arrangement, when the longitudinal cursor 23 is moved along the longitudinal track 12, the balance weight 75 moves in a counter direction the same distance as the cursor 23, keeping the balance of the drafting head assembly 24.

One of the characteristic features of the present balance means 27 lies in the construction of the balance weight 75 wherein a plurality of transversely obliqued grooves 79 is provided preferably in the under surface 80 of the balance weight 75. By providing the transversely obliqued grooves 79, the dusts deposited on the inner surface 81 of the bottom 82 of the longitudinal track 12 may be wiped off by the balance weight 75 and collected in the grooves 74 as the balance weight 75 slides on and along the bottom 82, whereby the creak of the balance weight 75 caused by the blocked dusts, that might occur in using usual balance weights, may be prevented and the smooth movement of the balance weight and the longitudinal cursor may be obtained.

Another characteristic feature of the present balance means 27 lies in that the end of the rope 78a adjacent the longitudinal cursor 23 includes a tension Spring 83 anchored at its one end to the longitudinal cursor 23 by means of a set screw 84, as illustrated in FIG. 7, or to a lug 85 integrally formed with a plate 80 that is a part of the longitudinal cursor 23, to which lug 85 being anchored the end of the other rope 78b as illustrated in FIGS. 4 and 4A, and also lies in that the longitudinal cursor 23 has notches 86 formed in the center of each of its opposite ends through which each of the ropes 78a and 78b extends from the bottom side to the upper side of the longitudinal cursor 23 as illustrated in FIG. 4 to thereby form a stepped portion in the rope line. The formation of the stepped portion in the rope line will produce a tension proportional to the stepped portion in the rope which has been extended normally or without a slack between the longitudinal cursor 23 and the balance weight 75, in other words, the notch 86 is a simple rope tensioning means.

Another characteristic feature of the present balance means 27 lies in the constructions of the end caps 21 and 22 supporting the sheaves 76 and 77 respectively. Since the end caps 21 and 22 are of the same construction, the explanation thereof will be made with reference to FIG. 8 showing the lower end cap 22. The end cap 22 comprises a head 90, two spaced legs 91a and 91b positioned adjacent to the opposite ends of the head '90 to leave shoulders 92 thereon, and a pin 93 extending between the legs 91a and 91b and at its opposite ends press-fitted in openings 94a and 94b formed in the legs 91a and 91b respectively. The sheave 77 is mounted freely rotatably but without transverse movement on the pin 93, and its diameter is designed not to extend beyond the innermost edges of the legs 91a and 91b. The transverse track 12 includes liners 95a and 95b secured to the side walls of the track facing to the legs 91!! and 91b, and the liners 95a and 9511 are slidingly contacted with the legs 91a and 91b. The outer edges of the liners 95a and 95b are engaged by the shoulders 92 of the head 90 for prevention of the inward movement of the cap 22.

With this arrangement, even if the longitudinal cursor 23 is rapidly and carelessly moved to the upper end cap 21, and thereby the balance weight 70 is rapidly moved to the lower cap 22 to strongly strike it, the impact of the balance weight 70 on the lower cap 22 will be greatly damped by virtue of the resilient elongation of the spring 83 and the sliding movement of the lower end cap 22, consequently the damage of the lower end cap 22 or sheave 77 and/ or the breaking of the rope due to a sudden stretch thereof will be prevented. In a previous balancing means without the improved arrangement above mentioned, the troubles such as the damage of the end cap and the break of the rope has been experienced by the user.

According to the present invention, several difficulties encountered in use of the previous track type drafting machine may be removed.

What I claim is:

1. In a track type drafting machine for a drafting board comprising a transverse and a longitudinal track positioned perpendicularly to each other, said longitudinal track being generally tubular, means for locking the device to a drafting table, said transverse track having a cursor sildably mounted thereon, means for locking said cursor to its track, said cursor being provided with a pivotable mounting for the longitudinal track, said mounting having a track accommodating recess formed therein, said longitudinal track being mounted in said recess, said mounting being provided with means for compressing said recess to lock said track firmly therein, said longitudinal track being provided with a slidable cursor, a counter weight slidably mounted within the tubular chamber of the longitudinal track, the channel abutting surfaces of the counterweight being diagonally grooved.

2. In a track type drafting machine for a drafting board comprising a transverse and a longitudinal track positioned perpendicularly to each other, said longitudinal track being generally tubular, means for locking the device to a drafting table, said transverse track having a cursor slidably mounted thereon, means for locking said cursor to its track, said cursor being provided with a pivotable mounting for the longitudinal track, said mounting having a track accommodating recess formed therein, said longitudinal track being mounted in said recess, said mounting being provided with means for compressing said recess to lock said track firmly therein, said longitudinal track being provided with a slidable cursor, a counterweight slidably mounted within the tubular chamber of the longitudinal track, pulley supported cables connecting said counterweight with the longitudinal cursor so that the movement of the cursor causes a corresponding movement of the counterweight to balance the drafting head assembly, a tension spring connecting the longitudinal cursor with one of the flights of cable an opening formed in the longitudinal cursor so the cable can pass from its underside to its upperside for exerting tension on the cable.

References Cited UNITED STATES PATENTS 1,789,125 1/1931 Wilderson 33-79 3,047,954 8/1962 Hislop 33-76 1,313,520 8/1919 Cole 33-79 FOREIGN PATENTS 1,347,620 11/1963 France 3379 HARRY N. HAROIAN, Primary Examiner 

